c++ - C++14 中 main() 的合法定义

Question

我能找到的 C++14 的最后一个草稿说，关于 main() [3.6.1]:

An implementation shall not predefine the main function. This function shall not be overloaded. It shall have a return type of type int, but otherwise its type is implementation-defined. All implementations shall allow both

— a function of () returning int and

— a function of (int, pointer to pointer to char) returning int

和(第 5 段)

If control reaches the end of main without encountering a return statement, the effect is that of executing

return 0;

这是否意味着以下所有的都是合法的 C++14 最小程序？如果没有，为什么不呢？

1. auto main() -> int {}
2. auto main() { return 0; }
3. auto main() {}

Answer 1

1. 合法，第二个和后者不合法，原因如下:

2. 由于CWG 1669被接受，因此无法推断主函数的返回类型，标准将改写为:

   An implementation shall not predefine the main function. This function shall not be overloaded. It shall have a declared return type of type int, but otherwise its type is implementation-defined.

   这进入了 n4140。更多信息:http://wg21.cmeerw.net/cwg/issue1669

3. 同上